1. Field of the Invention
This invention relates to certain new compounds derived from fluorene-9-carboxylic and fluorene 1-carboxylic acids, to plant-growth regulating compositions containing these compounds and to their use for regulating plant growth.
2. Prior Art
A series of patents obtained by E. Merck AG, Darmstadt, Germany, are directed to various derivatives of fluorenecarboxylic acid useful for modifying plant growth patterns. These compounds which have become known as morphactins due to their singular mode of plant growth control, are described and/or claimed in U.S. Pat. Nos. 3,476,545; 3,598,564; 3,506,434; 3,746,740; 3,830,643; and 3,843,714. Of the many compounds described, methyl-2-chloro-9-hydroxyfluorene-9-carboxylate(chlorflurenol-methyl), in particular, has become commercially available as MAINTAIN CF-125 for use as a general plant growth retardant and weed suppressant, either by itself or in combination with other growth-affecting chemicals. However, in many instances, it has proved phytotoxic to the plants being treated.
We have now discovered and developed still different, novel derivatives of fluorenecarboxylic acid which likewise are useful as plant growth modifiers, primarily for regulating flower and fruit set in cultured plants without phytotoxic effects thereto. Particularly, those of our compounds preferred for use at this time may significantly modify the growth patterns of plants and enhance commercially important crop yields therefrom, even when employed in minute quantities.